Field of the Invention
The present invention is broadly concerned with the use of hot waste gases from a heat engine used in electrical generation, to dry salt, sulfate of potash, or magnesium chloride minerals within process dryers such as rotary kiln dryers, fluidized bed dryers, or dispersion dryers. Even more preferably, at least some portion of the electrical power that is generated is used for running plants and equipment, such as those used for manufacturing those minerals.
Description of the Prior Art
Drying processes for salt (sodium chloride) and similar products, such as sulfate of potash and magnesium chloride, typically utilize either direct fired natural gas heating or indirect heating through heat exchangers, with steam or a hot oil fluid providing the heat. These dryers may be a rotary kiln dryer of either counter-current or co-current design, a fluidized bed dryer, or a dispersion dryer. While effective, direct fired heating is very inefficient (35-40%) and much energy is lost to the environment. Heating with steam or hot oil is also effective, but also has efficiency limits since the heat energy passes through at least two steps to dry the process material. There is need for a drying system for salt and similar products with an improved efficiency from multiple uses of the energy input into the system (above 75%).